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Multi-Way Conventional loudspeakers with crossovers

rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
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Old 2nd January 2019, 08:17 PM   #2621
mark100 is online now mark100  United States
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Hey POS,
Could a FIR file be built that has coefficients built to regular impulse centering,
and also have coefficients that apply only to certain frequencies at a time later than the frequencies initially went thru?

I bet that made no sense at all...LoL..

Here's the example/goal....
Say a CD driver/horn has a 2000Hz reflection head back into the horn throat caused from discontinuity in the horn mouth.
That reflection back to the throat then rebounds back out the horn in delayed fashion ( vs the ongoing signal).

Is there a way that the 2000Hz reflection could be be nulled with a small out of polarity 2000Hz 'injection' at the appropriate time?
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Old 3rd January 2019, 10:12 PM   #2622
pos is offline pos  Europe
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Originally Posted by TNT View Post
The "FFT-length" - how does it impact the generated filter? Is there a limit in the target HW (e.g. DAM DAC) to be considered?

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Originally Posted by thierry38 View Post
FFT lenght defines resolution at low frequency.(and ripple treshold)


Depends of sampling frequency.


More lenght,(taps) more resolution in the lows.(steepness slope and high Q).
Same as windowing impulse with REW,Holm,Arta...
The "FFT length" parameter in rephase is only used for internal calculations and mainly impacts result visualization apparent resolution, and iterative optimization behavior (to a point). What matters most is the number of taps, and this is what Thierry describes.

You can leave FFT length at its default setting and not worry about it.
I should probably just hide this parameter in future versions...
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2019-01-16: rePhase 1.4.3
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Old 3rd January 2019, 10:16 PM   #2623
TNT is offline TNT  Sweden
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OK so if I generated two filters where the only difference was the "FFT-length", both files would be identical?

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Old 3rd January 2019, 10:26 PM   #2624
pos is offline pos  Europe
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Quote:
Originally Posted by mark100 View Post
Hey POS,
Could a FIR file be built that has coefficients built to regular impulse centering,
and also have coefficients that apply only to certain frequencies at a time later than the frequencies initially went thru?

I bet that made no sense at all...LoL..

Here's the example/goal....
Say a CD driver/horn has a 2000Hz reflection head back into the horn throat caused from discontinuity in the horn mouth.
That reflection back to the throat then rebounds back out the horn in delayed fashion ( vs the ongoing signal).

Is there a way that the 2000Hz reflection could be be nulled with a small out of polarity 2000Hz 'injection' at the appropriate time?
Hi Mark

Never tried this myself, but from the top of my head that should/could be doable by mixing (with sox, audacity, etc.) the initial FIR with a second one generated from identical settings but with an added delay, inverted polarity, and EQ/gain to mimic what really goes back to (and off!) the throat...
Good luck measuring and identifying the proper parameters though
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Last edited by pos; 3rd January 2019 at 10:28 PM.
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Old 3rd January 2019, 10:27 PM   #2625
pos is offline pos  Europe
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Originally Posted by TNT View Post
OK so if I generated two filters where the only difference was the "FFT-length", both files would be identical?

//
If you are not using iterative optimization, yes, even if the result curves do not look the same down low.
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Old 3rd January 2019, 10:56 PM   #2626
3ll3d00d is offline 3ll3d00d  United Kingdom
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Quote:
Originally Posted by mark100 View Post
Is there a way that the 2000Hz reflection could be be nulled with a small out of polarity 2000Hz 'injection' at the appropriate time?
This sounds the same as the virtual bass array approach that I have seen (and have implemented myself) using acourate, details in Virtual Bass Array | Digital Room Correction

I would be slightly surprised if this is feasible/useful at 2kHz though
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Old 3rd January 2019, 11:22 PM   #2627
mark100 is online now mark100  United States
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Quote:
Originally Posted by pos View Post
Hi Mark

Never tried this myself, but from the top of my head that should/could be doable by mixing (with sox, audacity, etc.) the initial FIR with a second one generated from identical settings but with an added delay, inverted polarity, and EQ/gain to mimic what really goes back to (and off!) the throat...
Good luck measuring and identifying the proper parameters though
Good luck needed !! Lol
But hey, this paper just linked by brinkman in another thread gives me hope http://mariobon.com/Articoli_storici...s_ETF2010d.pdf

Thanks POS


@3ll3d00d....cool, must study your post
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Old 4th January 2019, 12:03 AM   #2628
pos is offline pos  Europe
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Originally Posted by 3ll3d00d View Post
This sounds the same as the virtual bass array approach that I have seen (and have implemented myself) using acourate, details in Virtual Bass Array | Digital Room Correction
Very interesting! Is this your website and system?
That makes me want to experiment with all this!
One more feature on the todo list for rephase 1.5.0 I guess
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Old 4th January 2019, 12:10 AM   #2629
pos is offline pos  Europe
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Originally Posted by mark100 View Post
Good luck needed !! Lol
But hey, this paper just linked by brinkman in another thread gives me hope http://mariobon.com/Articoli_storici...s_ETF2010d.pdf
You can think of addressing what is reflected from the mouth back to the throat and remitted from there, but you cannot address what is directly diffracted /emitted from the mouth (or any discontinuity in the profile for that matter) to the listener, because this will change from one position to another.
Unfortunately the latter is probably more audible than the former.
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Old 4th January 2019, 07:35 AM   #2630
3ll3d00d is offline 3ll3d00d  United Kingdom
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Very interesting! Is this your website and system?
sorry, didn't mean to give the impression that is my website, I just meant I have previously used that approach in my system (and that site is the one I remember that documented it).
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